1. Technical Field of the Invention
The present invention relates to a device for optical excitation/detection including an arrayed plurality of photodetectors and photoemitters and, in particular, to such a device manufactured using discrete semiconductor photoemitter devices.
2. Description of Related Art
Detector arrays (i.e., devices comprising an arrayed plurality of photodetectors) can be fabricated using well known complementary metal oxide semiconductor (CMOS) fabrication techniques. Such arrays are typically of very high quality, exhibit low noise and are inexpensive to produce. What is lacking with conventional CMOS fabrication techniques for such devices is a way of easily incorporating a plurality of light emitting devices (for example, light emitting diodes (LEDs), laser diodes, or other type photoemitters) into the CMOS array detector device. For example, standard solid state light emitting devices (like LEDs) are difficult to incorporate onto a CMOS detector array because the process for solid state LED photoemitter fabrication is incompatible with the CMOS fabrication process used to form the photodetectors. This, generally speaking, precludes the co-development of CMOS photodetectors and solid state LED photoemitters on the same substrate. It is further recognized that solid state photoemitter light sources are generally edge-emitters. This requires that the semiconductor substrate for the LED (that is generally built by layering-up using planar processes to form the photoemitter) be diced and placed on edge when assembled with the CMOS photodetectors. This manufacturing option is quite difficult to achieve reliably, efficiently and inexpensively using conventional assembly processes.
What is needed is a device for optical excitation/detection, and a method for making such a device, that includes an arrayed plurality of CMOS photodetectors and discrete semiconductor photoemitter devices.
One embodiment of the present invention comprises an optical excitation/detection device utilizing a CMOS fabricated photodetector array. The CMOS array includes an arrayed plurality of photoreceptor areas and photoemitter areas. Each photoreceptor area includes a CMOS integrated photoreceptor, and each photoemitter area includes at least two buried electric contact pads. A plurality of recessed regions are formed in a top surface of the CMOS array at the locations of the photoemitter areas to reveal the buried electric contact pads. Discrete semiconductor photoemitter devices are then inserted into, and mechanically retained within, the recessed regions of the CMOS fabricated photodetector array. Electrical contact is established between the inserted discrete semiconductor photoemitter devices and the revealed buried electric contact pads to form an optical excitation/detection device that includes an arrayed plurality of CMOS photodetectors and discrete semiconductor photoemitters.
A method for assembling an optical excitation/detection device in accordance with an embodiment of the present invention etches back a top surface of a CMOS fabricated photodetector array that includes an arrayed plurality of photoreceptor areas and photoemitter areas, wherein each photoreceptor area includes a CMOS integrated photoreceptor, and each photoemitter area includes at least two buried electric contact pads. The etch back reveals the buried electric contact pads at each photoemitter area. A discrete semiconductor photoemitter device is then inserted into, and mechanically retained within, each of the recessed regions of the CMOS fabricated photodetector array. Electrical contact is established between the inserted discrete photoemitter devices and the revealed buried electric contact pads to form an optical excitation/detection device that includes an arrayed plurality of photodetectors and discrete semiconductor photoemitters.